Both of my sons have had occassional wax build-up, mostly my currently ten-year-old. We've used mineral oils and other over-the-counter wax softening agents, but have found hydrogen peroxide to work best. Cam is ten now, so he gets out a towl, the ear bell syringe and the peroxide when I tell him it's time to clean his ears. A little pen light is useful to see what's going on in there.
To loosen up the buildup, tilt your child's head to the side as if sleeping on a pillow. My son is older and can sit on the toilet and lay his head on the towel on the bathroom cabinet, but when he was little, I sat on the floor and he laid his head on a big towel rolled up like a pillow. Drip peroxide into the ear canal and wait a minute. Then rotate to the other ear after your little one tips her head to let the first ear drain. The residue will fizz a little while you work on the other. Now that my son has more patience, I do this until the fizzing is very slow.
Peak into the canal with a flashlight occassionally, and don't be surprised with what you see -- the peroxide will make debris soft, large and white.
I do this about two times each, then I fill a clean sink with warm water that will not be shocking to the inside of a warm child's ear. It is a good idea to do this part after your little one is in the tub - the splashing/draining ear water can drain onto the tub. (Better yet, fill a large bowl with the warm water, and let your daughter lean over the closed bathroom sink so you can see what washes out.) My son lets it drain into a big fluffy towel.
Just use the bulb syringe and flush out any loose debris, alternating ears. Be gentle, don't be a water jet! Too fast and it hurts. Let your daughter be your guide.
Once I found the tip to a colored pencil that he couldn't remember using at school for a tickle! Oh, my! Kids!!
~~V. L.